Probs with an Explorer

[MonkeyGein]

so my friend's exploder has be running rough, burning thru gas and threw some codes in his face.
1998 w/4.0
misfire cyln 4
misfire cyln 6
bank 1 lean
bank 2 lean

what does the "bank 1/2" mean?

my scanner is showing the MAF getting a reading that changes with moar air flow. what is a normal MAF reading?
Maf visibly looks clean
changed the fuel filter

i'm thinking that the comb of the codes are significant and wiill be able to narrow down the cause of the problem quicker/easier.

thanls

 

[lil'mounty]

Well, "bank 1 2 lean" (too little gas to air ratio) is O2 sensors. Could it be so lean it misfires. Any lack in performance will cause poor MPG, Like driving a 6000 lb 4-clylinder which is supposed to be a 6-cyl. (takes a lot more work to get the job done). If it were me..... I would replace the o2 sensors (just front) and clean the MAF with MAF spray. Even if it looks clean. Unplug the negative for awhile and try again. If you start messing with the plugs right off the bat, you can count on replacing plugs and wires from flexing the wires. Start w/ o2 sensors and MAF. IMO.

 

[crazymind]

Try changing the gasket between the upper and lower intake. My 99 was throwing lean codes and idle like hell when cold I change those gaskets and haven't had a problem since.

 

[Roadrunner777]

Bank 1 is the driver's side of the block, Bank 2 is passenger side. Each has it's own O2 sensor, so you are looking at something making both sides lean.

For MAF, try this site:

http://easyautodiagnostics.com/ford_maf/maf_sensor_ford_1.php

Take off the plastic tube from the MAF to the Throttle Body and inspect the joints and underside for any cracks or damage. A leak here will cause engine lean.

Low fuel pressure will do this too.

Take some carb cleaner and spray it around the intake manifold with the engine running. If you get a change in idle, follow that spray. I don't think it's here because it's hitting both banks, just saying.

Also, vacuum leaks. Pinch off the tubes on the vacuum tree and see if you get a change.

 

[MonkeyGein]

wouldn't it just say it was an O2 sensor if it was an O2?

the plugs and wire seem fine..... or at least don't seem like an immediate problem right now. there was a change in how it ran when i disconected the plug wires on those cyln.

good idea of pinching off the vac hoses, i never would have thought of checking them that way. i read about the gasket leak. i suppose that's a cheap fix but time consuming.

 

[crazymind]

Its not too bad the first time I did it, it took me bout twenty minutes and that's on a sohc

 

[Roadrunner777]

Let's go back and talk about engine control. The computer determines the amount of fuel to inject based mainly on airflow from the MAF, and the Throttle position sensor. It uses other sensors like temperature for trimming, but the MAF and TPS are the main players. So, it takes those readings, predicts the best amount of fuel to inject, and signals the injectors.

The O2 sensors are mainly used for feedback... how close was the computer's prediction to the best mixture. In your case, the O2 sensors are responding that the computer's prediction was too lean. The O2 sensors are fine, they are doing exactly what they are supposed to do.

So, the big question is: Why is the engine lean? Two simple answers: Too much air, or not enough fuel. My earlier response suggests troubleshooting to that effect.